Crystal-Site Engineering of Novel Na3kmg7(Po4)6-X(Bo3)X: Eu2+ Phosphor for Full-Spectrum Lighting

Abstract

The “cyan gap” is the bottleneck problem in violet driven full-spectrum white-light-emitting diodes (wLEDs) healthy lighting. Accordingly, we develop a novel broadband-blue-cyan emission Na3KMg7(PO4)6-x(BO3)x: Eu2+ (NKMPB: Eu2+) phosphor via the crystal-site engineering. This phosphor, derived from the Na3KMg7(PO4)6: Eu2+ phosphor, shows the desired abundant cyan emissive components. A comparative study is conducted to reveal the microstructure-property relationship and the key influential factors to its spectrum distribution. It can be found that the introduced (BO3)3− units can manipulate the site-selective occupation of Eu2+ activators, asymmetrically broadening the emission spectrum in NKMPB: Eu2+. Considering detailed luminicence perforamnce analysis and the density functional theory calculations, new substitution pathway of Eu2+ is created by substituting (PO4)3− with (BO3)3− units, making partial Eu2+ ions enter the Mg2+ (CN = 5, CN = 6) crystallographic sites, and yielding an extra emission band at 600 nm (16667 cm-1) and especially 501 nm (19960 cm-1). Meanwhile, a high-color-quality full-spectrum-emitting wLEDs was fabricated, upon 100 mA forward-bias current driven. Due to the achieved extra cyan emissive components of NKMPB: Eu2+, the constructed NKMPB: Eu2+-based wLEDs shows better color rendering ability (~90.9) than that of Na3KMg7(PO4)6: Eu2+-based wLEDs (~86.3), and also demonstrates its great potential in the full-spectrum healthy lighting.

Keywords: Phosphor, Full-Spectrum Lighting, Crystal-site Engineering, Eu2+-activatedLuminescent Materials